(1) Technical Field
The invention relates to a rotary fuel pump for pumping fuel along a fuel line in which a hollow pulse dampener is disposed in the path of fuel flowing through the system for dampening pressure pulses in a fuel system.
(2) Description of the Prior Art
One of the major concerns in the design, engineering and manufacture of the automobile is maintaining a quiet ride. In meeting these concerns, the automotive industry has endeavored to reduce, dampen or eliminate, as much as possible, the noise sources in the vehicle. One source of noise in the vehicle is derived from pressure pulses in a pressurized fuel line. Positive displacement fuel pumps as well as the on and off action of fuel injectors can cause undesirable "pulses" which create unwanted noise in the system.
Pulse dampeners are known in the prior art. Typically, in automotive applications, a diaphragm-type accumulator is disposed along the fuel line between the fuel pump and the injectors. The pressurized fuel flows through an axial passage in the pulse dampener which includes an aperture which exposes a flexible diaphragm to the pressurized fuel. When a pressure pulse exceeds a predetermined level, the diaphragm flexes, thereby dampening the pressure pulses and smoothing out this operating parameter. This type of pulse dampener is relatively complex and expensive as compared to the subject invention.
Pulse dampeners have also been employed to dampen the pressure pulses in water pumps and to reduce "water hammer" in plumbing. For example, an air filed rubber annulus which is yieldable to the pressure pulses generated by a water pump disposed in a well is disclosed in U.S. Pat. No. 2,473,726 issued to Payne on Jun. 21, 1949. Similar attempts have been made to reduce noise and dampen pulses in fuel systems by employing flexible members, typically made of a rubber based material, disposed in-line in the fuel system for absorbing and dampening the pulses. The desirable characteristics of these types of pulse dampeners in the prior art typically degrade with time when the material is exposed to gasoline or methanol.
Heretofore, there has been no cost effective efficient way to dampen pressure pulses in a fuel system using a pulse dampener disposed in-line of the system and which is constantly exposed to or immersed in the fuel.
The pulse dampener of the subject invention is manufactured using an apparatus and method which utilizes blow-mold technology. Methods and apparatus for making products using blow-mold technologies are known in the prior art. However, heretofore, it has not been possible to manufacture a pulse dampener of the subject invention utilizing blow-mold technology as described below. The subject invention addresses these deficiencies in the prior art in a very efficient, durable, and effective fuel pump system having a pulse dampener disposed along the path of fuel flowing through the system.